British tree died — remains rot (10)
I believe the answer is:
balderdash
'rot' is the definition.
(I've seen this in another clue)
'british tree died remains' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'tree' becomes 'alder' (alder is a kind of tree).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'remains' becomes 'ash' (remains of a fire).
'b'+'alder'+'d'+'ash'='BALDERDASH'
(Other definitions for balderdash that I've seen before include "Senseless talk/writing" , "Senseless talk" , "Twaddle" , "cobblers > GAME" , "Piffle" .)